Thin film transistor, array substrate and display device

ABSTRACT

The present invention provides a thin film transistor, an array substrate and a display device. The thin film transistor comprises an active layer, a source electrode and a drain electrode. The active layer comprises a source electrode contact region and a drain electrode contact region, and a semiconductor channel region arranged between the source electrode contact region and the drain electrode contact region. A conductive layer is provided on the semiconductor channel region and is spaced apart from the source electrode and the drain electrode.

FIELD OF THE INVENTION

The present invention relates to the field of display technology, andparticularly to a thin film transistor, an array substrate and a displaydevice.

BACKGROUND OF THE INVENTION

Display technology has been widely applied in a television, a mobilephone and display of public information, and currently, liquid crystaldisplay panel and organic light-emitting display (OLED) panel are mostwidely used.

Both the liquid crystal display panel and the OLED panel comprise anarray substrate and a display unit formed on the array substrate. Thearray substrate comprises a plurality of thin film transistors. In aliquid crystal pixel circuit, the thin film transistor functions as aswitch. In driving an OLED, the thin film transistor functions as both aswitch and a driver. In the prior art, when the thin film transistorserves as a driving transistor, its drive capability is in positivecorrelation with conductivity of an active layer of the thin filmtransistor. The active layer is made of a semiconductor material whoseconductivity is relatively low as compared to a conductive material.Therefore, it is of great importance to enhance the conductivity of theactive layer.

SUMMARY OF THE INVENTION

In view of the problem that the active layer of the existing thin filmtransistor has poor conductivity, the technical problem to be solved bythe present invention includes providing a thin film transistor withimproved conductivity, an array substrate comprising the thin filmtransistor and a display device comprising the array substrate.

According to an aspect of the present invention, there is provided athin film transistor, which comprises an active layer, a sourceelectrode and a drain electrode, and the active layer comprises a sourceelectrode contact region and a drain electrode contact region, and asemiconductor channel region arranged between the source electrodecontact region and the drain electrode contact region. A conductivelayer is provided on the semiconductor channel region and is spacedapart from the source electrode and the drain electrode.

Since the conductive layer is provided on the semiconductor channelregion of the active layer of the thin film transistor according to thepresent invention, when a voltage is applied to the gate, charges with apolarity opposite to charges of the gate will be induced at a side ofthe conductive layer close to the gate, and therefore an electric fieldmay be formed between the gate and the conductive layer, thus enhancingthe electric field in the active layer to strengthen the conductivity ofthe semiconductor channel region and make the conductivity of the thinfilm transistor better.

According to an embodiment of the present invention, a material of theactive layer may be any one of amorphous silicon, polycrystallinesilicon, microcrystalline silicon, and oxide semiconductor.

According to an embodiment of the present invention, the active layermay further comprise an ohmic contact layer, and the source electrode,the drain electrode and the conductive layer may be in contact with thesource electrode contact region, the drain electrode contact region andthe semiconductor channel region through the ohmic contact layer,respectively.

According to an embodiment of the present invention, the conductivelayer may be a metal conductive layer. The source electrode, the drainelectrode, and the conductive layer may be provided in the same layerand made of the same material.

According to an embodiment of the present invention, a material of thesource electrode, the drain electrode, and the conductive layer may beany one of Mo, Mo—Nb alloy, Al, Al—Nd alloy, Ti and Cu.

According to an embodiment of the present invention, the semiconductorchannel region may be rectangle shaped or U-shaped.

According to an embodiment of the present invention, the conductivelayer may comprise one or more conductive parts.

According to an embodiment of the present invention, the thin filmtransistor may further comprise a gate which is arranged above or belowthe active layer and is spaced apart from the active layer by a gateinsulation layer.

According to another aspect of the present invention, there is providedan array substrate, which comprises the thin film transistor accordingto the present invention.

According to another aspect of the present invention, there is provideda display device, which comprises the array substrate according to thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a structure of an array substratecomprising a thin film transistor according to an embodiment of thepresent invention;

FIG. 2 is a sectional view taken along line A1-A2 of FIG. 1;

FIG. 3 is a schematic diagram of another structure of an array substratecomprising a thin film transistor according to an embodiment of thepresent invention;

FIG. 4 is a schematic diagram of still another structure of an arraysubstrate comprising a thin film transistor according to an embodimentof the present invention;

FIG. 5 is a sectional view taken along line B1-B2 of FIG. 4; and

FIG. 6 is a schematic diagram of yet another structure of an arraysubstrate comprising a thin film transistor according to an embodimentof the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In order to make a person skilled in the art better understand thetechnical solutions of the present invention, the present invention willbe further described in detail below in conjunction with theaccompanying drawings and specific implementations.

FIG. 1 is a schematic diagram of a structure of an array substratecomprising a thin film transistor according to an embodiment of thepresent invention, and FIG. 2 is a sectional view taken along line A1-A2of FIG. 1.

Referring to FIGS. 1 and 2, the thin film transistor according to theembodiment of the present invention comprises a gate 11, an active layer13, a source electrode 21 and a drain electrode 22 which are formed on asubstrate 1. The active layer 13 comprises a source electrode contactregion and a drain electrode contact region configured to be connectedto the source electrode 21 and the drain electrode 22, respectively, anda semiconductor channel region arranged between the source electrodecontact region and the drain electrode contact region. A conductivelayer 25 is provided on the semiconductor channel region and theconductive layer 25 is spaced apart from the source electrode 21 and thedrain electrode 22.

Since the conductive layer 25 is provided on the semiconductor channelregion, when a voltage is applied to the gate 11, charges with apolarity opposite to charges of the gate 11 will be induced at a side ofthe conductive layer 25 close to the gate 11, and therefore an electricfield is formed between the gate 11 and the conductive layer 25, thusenhancing the electric field in the active layer 13 to strengthen theconductivity of the semiconductor channel region and make theconductivity of the thin film transistor better.

A material of the active layer 13 may be any one of amorphous silicon,polycrystalline silicon, microcrystalline silicon, and oxidesemiconductor.

FIG. 3 is a schematic diagram of another structure of an array substratecomprising a thin film transistor according to an embodiment of thepresent invention

Referring to FIG. 3, this embodiment differs from the embodiment shownin FIG. 2 in that the active layer 13 comprises a semiconductor layer131 and an ohmic contact layer 132 provided on the semiconductor layer131. The ohmic contact layer 132 is in contact with the source electrode21, the drain electrode 22 and the conductive layer 25. The ohmiccontact layer 132 facilitates the contact between the semiconductorlayer 131 and the source electrode 21 and between the semiconductorlayer 131 and the drain electrode 22.

Referring to FIGS. 2 and 3, the conductive layer 25 may be a metalconductive layer. The source electrode 21, the drain electrode 22, andthe conductive layer 25 of the thin film transistor are provided in thesame layer and made of the same material, and thus the source electrode21, the drain electrode 22, and the conductive layer 25 may be formed atthe same time through one process. In addition, it is possible to formthe source electrode 21, the drain electrode 22, and the conductivelayer 25 separately.

The material of the source electrode 21, the drain electrode 22, and theconductive layer 25 of the thin film transistor may be one or morematerials selected from a group consisting of molybdenum (Mo),molybdenum niobium alloy (MoNb), aluminium (Al), aluminium neodymiumalloy (AlNd), titanium (Ti) and copper (Cu).

FIG. 4 is a schematic diagram of still another structure of an arraysubstrate comprising a thin film transistor according to an embodimentof the present invention, FIG. 5 is a sectional view taken along lineB1-B2 of FIG. 4, and FIG. 6 is a schematic diagram of yet anotherstructure of an array substrate comprising a thin film transistoraccording to an embodiment of the present invention.

The semiconductor channel region of the active layer 13 may be rectangleshaped or U-shaped. As shown in FIG. 4, the shape of the semiconductorchannel region may be a rectangle. As shown in FIGS. 1 and 6, the shapeof the semiconductor channel may be a U shape. In addition, thesemiconductor channel region may be of other shape than the U shape andthe rectangle.

Further, the conductive layer 25 may comprise one or more conductiveparts.

Referring to FIGS. 4 and 5, a conductive part is provided on thesemiconductor channel region of the active layer 13 and the conductivepart is located between the source electrode 21 and the drain electrode22 of the thin film transistor.

Referring to FIG. 6, the conductive layer 25 comprises conductive parts251 and 252 which are arranged in the same layer and spaced apart fromeach other. As shown in FIG. 6, the semiconductor channel region of theactive layer 13 is of a U shape. The conductive part 251 is located on acentral portion of the active layer 13 and between the drain electrode22 and the source electrode 21, so as to strengthen the conductivity ofthe semiconductor channel region between the drain electrode 22 and thesource electrode 21. The conductive part 252 is located at theupper-left corner of the active layer 13 and between the drain electrode22 and the source electrode 21, so as to strengthen the conductivity ofthe semiconductor channel region at the upper-left corner of the activelayer 13. The number and shape of the conductive part(s) are not limitedin the embodiment of the present invention and may be set as required.

The thin film transistor may be a top-gate thin film transistor or abottom-gate thin film transistor. When the thin film transistor is atop-gate thin film transistor, the gate 11 is arranged above the activelayer 13 and is spaced apart from the active layer 13 by a gateinsulation layer 12; when the thin film transistor is a bottom-gate thinfilm transistor, the gate 11 is arranged below the active layer 13 andis spaced apart from the active layer 13 by a gate insulation layer 12.The gate 11 may be a single layer or a multilayer laminate formed of oneor more materials selected from the group consisting of molybdenum (Mo),molybdenum niobium alloy (MoNb), aluminium (Al), aluminium neodymiumalloy (AlNd), titanium (Ti) and copper (Cu), for example, the gate 11may be a single layer or a multilayer laminate formed of Mo, Al or analloy containing Mo and Al. The gate insulation layer 12 may be amultilayer laminate formed of one or more materials selected from thegroup comprising silicon oxide (SiOx), silicon nitride (SiNx), hafniumoxide (HfOx), silicon oxynitride (SiON), aluminum oxide (AlOx) and thelike.

The thin film transistor according to the present invention may beapplied to various kinds of array substrates. A passivation layer 30 isprovided on the thin film transistor, the drain electrode 22 of the thinfilm transistor according to the present invention is connected to apixel electrode 32 through a via hole 31 penetrating through thepassivation layer 30, the source electrode 21 is connected to a dataline 20, and the gate 11 is connected to a gate line 10.

The array substrate comprising the thin film transistor according to thepresent invention may be applied to various display devices including,but not limited to, any products or components with a display function,such as a mobile phone, a tablet computer, a television, a display, anotebook computer, a digital photo frame, a navigator and the like.

It can be understood that, the above implementations are merelyexemplary implementations used for explaining the principle of thepresent invention, but the present invention is not limited thereto. Fora person skilled in the art, various modifications and improvements maybe made without departing from the spirit and essence of the presentinvention, and these modifications and improvements are deemed as theprotection scope of the present invention.

The invention claimed is:
 1. A pixel thin film transistor, comprising anactive layer, a source electrode and a drain electrode, wherein, theactive layer comprises a source electrode contact region and a drainelectrode contact region, and a semiconductor channel region arrangedbetween the source electrode contact region and the drain electrodecontact region, and a conductive layer is provided on the semiconductorchannel region and is spaced apart from the source electrode and thedrain electrode, wherein the pixel thin film transistor furthercomprises a gate, which is arranged below the active layer and is spacedapart from the active layer by a gate insulation layer, when a voltageis applied to the gate, charges with a polarity opposite to charges ofthe gate are induced at a side of the conductive layer close to thegate, wherein the semiconductor channel region is U-shaped when viewedin a plane view of the pixel thin film transistor, and the sourceelectrode comprises a U-shaped part corresponding to the U-shapedsemiconductor channel region, wherein the conductive layer comprises aplurality of conductive parts, and at least one of the plurality ofconductive parts is arranged between one end of the drain electrode andthe U-shaped part of the source electrode, and wherein the active layerfurther comprises an ohmic contact layer, and the source electrode, thedrain electrode and the conductive layer are in contact with the sourceelectrode contact region, the drain electrode contact region and thesemiconductor channel region through the ohmic contact layer,respectively.
 2. The pixel thin film transistor according to claim 1,wherein, a material of the active layer is any one of amorphous silicon,polycrystalline silicon, microcrystalline silicon, and oxidesemiconductor.
 3. An array substrate, comprising the pixel thin filmtransistor according to claim
 1. 4. The array substrate according toclaim 3, wherein, a material of the active layer is any one of amorphoussilicon, polycrystalline silicon, microcrystalline silicon, and oxidesemiconductor.
 5. The array substrate according to claim 3, wherein, theactive layer further comprises an ohmic contact layer, and the sourceelectrode, the drain electrode and the metal conductive layer are incontact with the source electrode contact region, the drain electrodecontact region and the semiconductor channel region through the ohmiccontact layer, respectively.
 6. The array substrate according to claim3, wherein, the source electrode, the drain electrode, and the metalconductive layer are provided in the same layer and made of the samematerial.
 7. A display device, comprising the array substrate accordingto claim
 3. 8. The display device according to claim 7, wherein, amaterial of the active layer is any one of amorphous silicon,polycrystalline silicon, microcrystalline silicon, and oxidesemiconductor.
 9. The display device according to claim 7, wherein, theactive layer further comprises an ohmic contact layer, and the sourceelectrode, the drain electrode and the metal conductive layer are incontact with the source electrode contact region, the drain electrodecontact region and the semiconductor channel region through the ohmiccontact layer, respectively.
 10. The display device according to claim7, wherein, the source electrode, the drain electrode, and the metalconductive layer are provided in the same layer and made of the samematerial.
 11. The pixel thin film transistor according to claim 1,wherein, the conductive layer is a metal conductive layer.
 12. The pixelthin film transistor according to claim 11, wherein, the sourceelectrode, the drain electrode, and the metal conductive layer areprovided in the same layer and made of the same material.
 13. The arraysubstrate according to claim 6, wherein, a material of the sourceelectrode, the drain electrode, and the metal conductive layer is anyone of molybdenum, molybdenum niobium alloy, aluminum, aluminumneodymium alloy, titanium and copper.
 14. The pixel thin film transistoraccording to claim 12, wherein, a material of the source electrode, thedrain electrode, and the metal conductive layer is any one ofmolybdenum, molybdenum niobium alloy, aluminum, aluminum neodymiumalloy, titanium and copper.